COMPARISON OF IMMUNE MECHANISMS IN VARIOUS EXPERIMENTAL MODELS OF CHOLERA

Abstract

Two of the main features of human cholera-induction of diarrhoea and confinement of the infection to the lumen of the intestinal tract-may be reproduced in three experimental models: (a) the streptomycin-treated, starved guinea-pig; (b) the intestinal loop in the adult rabbit; and (c) the suckling rabbit. In this paper the author compares the two last-mentioned models with his earlier work in guinea-pigs.Intestinal antibody (coproantibody) was highly protective, while circulating antibody had little or no effect, in all three models. The protective coproantibody was specific for the heat-stable vibrio antigens. It did not affect the growth of vibrios in the intestine, and its function may possibly be regarded as antitoxic rather than antibacterial. Oral vaccination protected adult rabbits against challenge by the loop technique. Heat-killed vaccine was as effective in this respect as live vaccine.The author feels that the present uncertainty concerning the protective value of cholera vaccination may be due to the fact that conventional vaccine is designed to induce high serum titres only. He considers that since oral vaccine has been shown to induce and maintain the production of coproantibody in human volunteers, a field trial should be carried out to determine whether coproantibody is as protective in man as it has proved to be in the experimental models.